Optical element and its manufacturing process

ABSTRACT

A method for manufacturing an optical device provides at least two sub-bodies of a base body and, at each sub-body, a surface so that the surfaces are complementary to each other and snugly fit on one another. Along at least one of the complementary surfaces, a first optical layer system is defined. The sub-bodies are joined along the complementary surfaces so as to embed the optical layer system between them and thus forming an assembled sub-body. Machining a continuous surface on the assembled sub-body and at a predetermined angle to the complementary surfaces and the embedded layer system then takes place, where the latter abut at the machined continuous surface. A second layer system is then provided along the continuous surface.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is a divisional of application Ser. No.08/756,140 filed Nov. 26, 1996 and now U.S. Pat. No. ______, whichclaims priority on Swiss application number 2694/96 filed Nov. 1, 1996.

FIELD AND BACKGROUND OF THE INVENTION

[0002] The present invention concerns an optical element that comprisesa base body and an optically effective layer system of which at leastone layer system surface contacts the base body.

[0003] The invention also comprises a related manufacturing process, theutilization of such a component or process, as well as an opticalprojection arrangement.

[0004] Introduction:

[0005] German patent reference DE-40 33 842 discloses a cuboid opticalelement composed of dichroitic layers referred to as a “dichroiticprism.”

[0006] In the present application the term X-cube is used.

[0007] The present invention starts with the problems that exist withknown X-cubes, as described, for example, in DE-40 33 842, or that occurin its manufacture. The present invention which was developed in orderto find a solution to the problems with such elements, can be applied toa number of other optical elements.

[0008] For this reason this description begins with the specificproblems to be solved on X-cubes and based thereon explains theapplication of the invention in more general terms.

[0009] Description:

[0010] Based on FIG. 1 the basic functional principle of an X-cube isexplained. Optical elements of this type are principally used inprojectors in order to recombine the red/green and blue channels in thespectral range of the visible light. As shown in FIG. 1 such an X-cube 1comprises four individual prisms 2 a to 2 d which can, for example, bemade of BK7 glass. In their cross-section they form right-angledisoceles triangles with an angle of 90 degrees, usually with a toleranceof over ±60 angular seconds, and hypotenuse angles of 45 degrees withtolerances of a few angular minutes. The length of the hypotenuse istypically between 5 mm and 50 mm, preferably 40 mm. Embedded between thetwo prism pairs 2 a and 2 b on the one side, 2 d and 2 c on the otherside, there is an optically effective layer system 5 that largelyreflects visible light in the blue range but largely transmits visiblelight in the green or red range. FIG. 1 shows a part of the bluereflector layer system as a color splitting system, labeled 5′, theother 5″.

[0011] Embedded between the two prism pairs 2 a and 2 d on the one side,2 b and 2 c on the other side there is an additional, opticallyeffective layer system 7, that largely reflects light in the red rangebut largely transmits light in the green range and the blue range. InFIG. 1 also the two legs of the red reflector layer system are shown asa color splitter system, labeled 7′ and 7″.

[0012] On the X-cube there are three input channels for red, green andblue light from corresponding sources, for example, LCD controlled, andan output channel with the recombined input signals. On the reflectorsystems, between each of said prism pairs, the correspondingly coloredlight, and particularly S-polarized light with an incidence angle ofless than 45 degrees is reflected. In addition the hypotenuse surfacesof the prisms 2 can be and usually are coated with an antireflectionlayer system.

[0013] Because the pixels of the red-blue-green input channels shouldconverge as accurately as possible, the angle tolerances on prism 2 andin the assembled X-cube must be very narrow.

[0014] Large tolerances result in poor imaging quality because thepictures do not accurately converge: blurring or color fringes occur.

[0015] Location 9, shown with dashes in FIG. 1 where the four individualprisms 2 meet, is also located within the imaging optical path. Opticalinterferences created in this location manifest themselves, as mentionedfor example, as a blurred picture in the output channel OUT. It is arequirement of such elements and their manufacturing process to minimizethe interferences, particularly in this location 9.

[0016] From DE-40 33 842, for example, it is known that X-cubes can bemanufactured from four prisms 2 according to FIG. 1. The four individualprisms are first manufactured in their exact dimensions through milling,grinding and polishing. Subsequently they are coated with theappropriate layer system along their leg and possibly on theirhypotenuse surfaces with an antireflection coating. Finally the coatedindividual prisms 2 are cemented together.

[0017] Disadvantages of the Known Processes and Known X-Cubes:

[0018] The handling effort required for manufacturing the X-cubes asdescribed, for example, in DE-40 33 842, is very high: First, each ofthe three lateral sides of each individual prism 2 must be mounted orfixed by plastering, blocking or wringing as shown in FIG. 1 before theglass can be worked. Subsequently the surfaces must be cleaned forcoating the individual prisms 2, and then mounted and dismounted for thecoating process. On an average two sides per individual prism need to becoated. This laborious handling considerably raises the production costsfor such X-cubes.

[0019] From FIG. 1, particularly location 9, it is evident that thecoating of the red and blue reflecting layer systems must be executed insuch a way that the coating does not wrap around the 90 degree edges ofthe individual prisms. This requires sophisticated coating fixtures ormasking of the legs on which no coating may be deposited. In thisrespect we refer U.S. Pat. No. 2,737,076 (Rock et al.).

[0020] During the coating and the handling of the individual prisms 2,the 90 degree prism edges are exposed without protection, that is,especially those edges which according to the foregoing explanation mustbe very accurate. This inevitably leads to chipping unless laboriousprecautions to protect these edges are taken, which again increases thecosts.

[0021] If, for example, anything goes wrong during the coating of theindividual prisms 2, such an individual piece must be remounted, ground,and repolished, otherwise it will have to be discarded. Correctionprocesses are at best very difficult to implement.

[0022] Cementing of the individual prisms 2 in the exact relativeposition is very difficult and laborious. Complicated processes such asdescribed in DE-40 33 842 are required. Prisms are cemented individuallywhich is time-consuming and therefore costly.

[0023] Independently of said disadvantages the known process results ina structure in location 9 as shown in FIG. 1, as can be seen from thedetail in FIG. 2. The same reference marks are used as in FIG. 1 areused. Item number 11 identifies the cemented joints.

[0024] From this it is evident that the cemented joints 11 cause aninterruption of the red light reflection layer system 7 (consisting of7′ and 7″) as well as the blue light reflection layer system 5(consisting of 5′ and 5″).

[0025] As the X-cube is manufactured by cementing the individual prisms2 whose 90 degree edges have been exposed to external influences withoutprotection, faults occur almost inevitably in location 9 due to chippingdefects along the 90 degree edges of the individual prisms.

SUMMARY OF THE INVENTION

[0026] The purpose of the present invention is to propose an opticalelement, in particular an X-cube, which is not afflicted by thedisadvantages explained on the basis of FIG. 2.

[0027] It is also the objective of the present invention to propose amanufacturing process that is not afflicted by said disadvantages inproduction, in particular of said X-cubes. The manufacturing process tobe found should by highly economical, afford greater accuracy, andrequire fewer process steps.

[0028] In an optical element of the type referred to at the beginning,this is achieved by deposition on the body, a second layer system thatadjoins the surface of the first layer system at an angle. In this waythe first mentioned, optically effective layer system is areallycontinuous and the second layer system adjoins one of the surfaces ofthe first one without a gap. A structure as has been explained based onFIG. 2 is avoided: According to the invention, with reference to FIG. 2,one of the layer systems, preferably 7, is continuous; individualsections 7′, 7″ no longer exist. According to the invention a secondlayer system, preferably system 5, 5′ adjoins that continuous layersystem 7, and in the case of an X-cube also a third layer system, 5″.The is not illustrated in FIG. 2 which shows the familiar intersectionstructures.

[0029] Characteristic for the process according to the invention is thatfor solving the aforementioned task one surface each is created on atleast two sub-bodies of the base body of the element, where said twosurfaces are complementary to each other on at least two sub-bodies,that is, they fit together with close tolerances. Subsequently at leastone of these complementary surfaces is coated with an opticallyeffective layer system, in particular the red or blue reflection layersystem, if the element to be produced is an X-cube.

[0030] Subsequently, said sub-bodies are joined, for example, bycementing along said complementary surfaces with their now embeddedlayer system. A composite sub-body is thus formed. On the compositesub-body one surface that is common to at least two sub-bodies isprocessed which is at an angle to the complementary, interconnectedsurfaces, so that the complementary surfaces along which the sub-bodiesare connected intersect the common surface to be processed. Finallyanother optically effective layer system is deposited along this jointlyprocessed surface.

[0031] The preferred design versions of the element or process accordingto the invention are specified in the dependent claims. The elementaccording to the invention is preferably used as an X-cube, or theprocess according to the invention is preferably used for manufacturingsuch X-cubes.

[0032] An optical projection arrangement with at least one elementdesigned as an X-cube according to this invention has significantlyreduced optical interference, especially in the center area 9 shown inFIG. 2, and due to the proposed production process it can bemanufactured more economically and more accurately.

BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The invention is subsequently explained by means of the followingillustrations:

[0034]FIG. 1 is a top view of an X-cube of the conventional type forexplaining the functional principle;

[0035]FIG. 2 is a central intersection area of the optically effectivelayer system on a conventional X-cube according to FIG. 1;

[0036]FIG. 3 is a perspective view of an intermediate product resultingfrom the process according to the invention, a product that is alreadyan optical element according to the invention;

[0037]FIGS. 4a to 4 h are intermediate products resulting from theprocess according to the invention, where the structures according toFIGS. 4f, 4 g and 4 h already represent an optical element according tothe invention;

[0038]FIG. 5 is an enlarged view showing the intersection area of thelayer system on the intermediate product according to the invention asshown in FIG. 4f;

[0039]FIGS. 6 and 7 are generalized optical element structures accordingto the invention with their layer system intersection areas;

[0040]FIG. 8 is an enhanced development of the optical elementillustrated in FIG. 5, or its intersection area according to theinvention;

[0041]FIG. 9 is a view like FIG. 8 but based on the intersection areashown in FIG. 5, showing an enhanced development of an element accordingto the invention;

[0042]FIG. 10 shows a central intersection area on an optical elementaccording to the invention, particularly as manufactured by theproduction process according to the invention, in comparison with thetraditional intersection area shown in FIG. 2 on traditional opticalcomponents of the X-cube type; and

[0043]FIG. 11 is a schematic representation of a generalized opticalelement according to the invention as can be realized with the aid ofthe present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0044] With respect to the production process of an X-cube according tothe invention, FIG. 3 shows already an intermediate product according tothe invention; it is the cuboid product from four sub-cubes 20 a to 20d. Between the sub-cube pairs 20 a and 20 d on the one side and 20 b and20 c on the other, there is a first optically effective layer system—forX-cube production and analogously to FIG. 1 layer system 7—whereasbetween the cube pairs 20 a and 20 b or 20 d, 20 c there is anotheroptically effective layer system, that is, in the X-cube production andwith respect to FIG. 1 layer system 5 with the parts 5′ and 5″. For theproduction of the X-cube length 1 of cube 22 is 1 to 8 X-cube lengths orgreater, in particular 4 X-cube lengths, in FIG. 1 measuredperpendicularly to the plane of the illustration. Basically this productwhose manufacturing steps will subsequently be explained, ischaracterized as follows:

[0045] All existing angles are 90 degrees (± tolerances), which meansthat the sub-bodies 20 and the intermediate product 22 are easy tomanufacture, because among others, the opposite sides can be machined atthe same time such as by dual lapping or dual polishing.

[0046] In simultaneous double-sided machining high parallelisms of themutually opposite surfaces can be achieved, for example, with deviationsof ≦2 μm across a length of 150 mm. In addition a high planarity of eachsurface is achieved, for example, with planarity deviations of ≦1 μmacross lengths of 150 mm.

[0047] Because all angles involved are 90 degrees (± tolerances), eachof the parts 20 a to 20 d and 22 can be easily mounted and positioned.In dual lapping or dual polishing operations no elaborate fixture isrequired and the corresponding part can simply be inserted into apolishing insert. Mounting of the parts by plastering, blocking orwringing can preferably be eliminated.

[0048] All angles involved can be manufactured with high precisionbecause they are all 90 degree angles and no angles of 45 degrees, forexample, that are much more difficult to produce. The angle tolerancesfor the 90 degree central angle of the sub-bodies 20 are preferably nogreater than ±20 angular seconds.

[0049] The measurement instrumentation for geometrically measuring theproduced parts can be kept very small by using an interferometer, forexample.

[0050] Particularly when plan parallel complementary surfaces to becemented are used, cementing is very easy and cemented joints ofaccurately defined thickness can be produced.

[0051] The production of such parts is easy to scale, that is, by usingplates of various sizes several workpieces 22 referred to as T-cubes canbe produced in a single piece that is subsequently singularized.

[0052] Optical measuring on coated surfaces of cuboid bodies with planparallel surfaces is much simpler than on triangular prisms.

[0053] The following step-by-step description based on FIGS. 4a to 4 cdescribes the manufacturing of body 22 shown in FIG. 3 which is alreadya product of the invention, is manufactured. It will become obvious thatthe disadvantages in the central area 9 as discussed on the basis ofFIG. 2 are actually eliminated with respect to layer arrangement andedge precision.

[0054]FIG. 4a shows a plate for blanks 20′.

[0055] Through dual lapping, mutually opposite surfaces are machinedaccording to FIG. 4b, particular the surfaces ∇∇.

[0056] Subsequently one of the surfaces ∇∇ of plate 20′ is coated with alayer system 5′ according to FIG. 4b, resulting in plate 20″.

[0057] If the manufacturing process described here involves theproduction of X-cubes, preferably and as shown in FIG. 4b the bluereflection system 5′ is deposited because the blue image may have moreblur than the red image due to the corresponding sensitivity of thehuman eye.

[0058] It should be noted here that the plate 20′ corresponds to thedimension of one or several elements, preferably four, in direction y aswell as direction x; a singularization in both dimensions will beperformed later.

[0059] According to FIG. 4c plates 20′ and 20″ are laminated, preferablyby cementing, in such a way that the aforementioned layer system,preferably the blue reflection system 5′, is embedded between them.

[0060] Whether only the surface of one of the plates 20″ involved iscoated or both, and correspondingly the cement film is located betweenthe surface of one plate 20′ and the layer, or between two layers,depends on the intended application. Preferred in the production ofX-cubes is the coating of one of the complementary surfaces involved,and cementing of this surface with the complementary surface of theuncoated plate 20″.

[0061] The term complementary surfaces is used because, as will be shownlater for other applications, the bodies with surfaces of any curvaturecan be placed on top of each other with the embedded layer system,provided the surfaces involved are complementary with the requiredaccuracy.

[0062] As shown in FIG. 4d the dual plates 20′ and 20″ are singularizedby sawing them into bars 24.

[0063] As shown in FIG. 4e the sawed bars 24 are tilted by 90 degreesand preferably two or more such bars are placed adjacent to each other,26, or as shown in the diagram on the left, an individual bar 24 isfurther processed.

[0064] For forming the plate 26 the bars must be aligned in such a waythat in the next processing step the second layer system which in theX-cube production is the red reflection system 7, is deposited exactlyperpendicular on the surface to be processed. This is greatly simplifiedby the fact that all surfaces of the bar or bars 24 are perpendicularand practically plan parallel to each other and because they areextremely flat. For example, as indicated at 25, preferably several bars24 can be wrought together in order to compensate any angular errorresulting from the sawing process. As mentioned and as shown on theleft, also individual bars 24 can be lapped or polished if the sawingprocess is sufficiently accurate. Lapping and polishing are given asexamples of joint mechanical machining.

[0065] As shown with ∇∇∇ the opposite lateral surface of plate 26 or ofthe individual bar 24 can now be dual lapped or dual polished.

[0066] As shown in FIG. 4f and as a very important step of thisinvention, one of the polished surfaces of the plate 26 or theindividual bar 24, in the first case for all bars 24 involved, arejointly repolished and subsequently coated. In the X-cube production ared reflection layer system 7 is deposited at this point, as shown inFIG. 4f.

[0067] In this way the first layer system 5 and the cementing film arefull-surface coated with 7 after repolishing. Preferably a relativelycold coating process is used, preferably a plasma and/or ion assistedcoating process, preferably a sufficiently cold PVD process, preferablysputtering, or PECVD process, but in particular a cold coating processwith substrate temperatures not exceeding 150 degrees C., preferably notexceeding 80 degrees C.

[0068] The structure of the process according to FIG. 4f and theprocedure proposed so far are inherently inventive, regardless ofwhether or not the layer systems represented with 5′ and 7′ aredeposited perpendicularly or obliquely to each other, and whether or notthe coated surfaces are plane or as mentioned above, complementarycurved. Intersections 9′ are created on which one layersystem—7—continuously overlaps the intersection of the second layersystem—5—.

[0069] According to FIG. 4g an uncoated plate 26 or an uncoatedindividual bar 24, after unwringing if applicable, and a coated plate26′ or a coated individual bar 24′ are placed on top of each other andcemented as shown in FIG. 4f. The layer system 5′ of the uncoated plate26 or the uncoated bar 24, as the third deposited layer system inaddition to the two systems 7 and 5′ on the coated plate 26′ or thecoated bar 24′, now becomes layer system 5″.

[0070] The resulting T-cube strips 28 are singularized into the desiredlengths 1. But before singularization for the production of the X-cubethe T-cubes are preferably chamfered by sawing and by machining theirsurfaces along planes E, preferably again on two sides, as shown withE1, E2, and E3, E4 respectively. After cutting to size in direction 1,very accurate X-cubes 1′ according to the invention are obtained. The 45degree angle tolerances do not exceed ±2 angular minutes, preferably nomore than ±1 angular minute. If applicable the chamfered surfacescorresponding to planes E in FIG. 4h are coated with an antireflectionsystem before the X-cubes are singularized.

[0071] Looking back at FIG. 4f, FIG. 5 is a detail 9′ of an opticalelement 1 according to the invention, as it occurs in the production ofX-cubes. In the latter a first optical layer system corresponding to 5′made of glass or plastic, preferably BK7 glass or polycarbonate or PMMA,which in X-cube production is the blue reflection system, is locatedbetween the plan parallel surfaces of the two separated bodies 20′, 20″(FIG. 4e, 4 d). The two bodies 20′, 20″ are cemented at 11′. After jointsurface finishing by polishing or lapping, layer system 5′ covered withcement film 11′, the second optical layer system corresponding to 7, inthe case of the X-cube a red reflection system, is deposited on bothbodies 20′ and 20′″. As can be seen from the comparison with FIG. 2, thebisectioning of 7 into 7′ and 7″ is eliminated through this invention.

[0072] Through this process the intersection area normally exhibits onlya slight indentation of the cement film 11′ as shown at 30 in FIG. 5,which has a maximum depth d with respect to the plane surface of layer 7of max. 5 μm, preferably max. 2 μm.

[0073]FIG. 6 shows in a generalized concept of FIG. 5 an optical elementaccording to the invention in which the second layer system 5′aintersects obliquely with the plane layer system 7 a.

[0074] In FIG. 7 the complementary surfaces of the bodies 20′b′, 20″bare curved, the same applies to the common surface coated with layersystem 7 b. In a highly defined manner layers 5′ and 7′ intersectaccording to FIG. 5, for X-cube production in particular at a rightangle. The one layer system—7—is continuous and in particular runs alsoacross the point of intersection. This is particularly important in allapplications where the intersection areas, for example corresponding to9′b in FIG. 7 or 9′a or 9′ in X-cube production, have an effect on theoptical path of the light influenced by the layer systems, in particularthe visible light. The professional now readily recognizes, particularlyin conjunction with FIG. 4, how analogously optical elements can also bemanufactured according to FIGS. 6 and 7, optical elements whichaccording to current knowledge have probably never been realized. Thisresults in completely new component structures that are suitable foroptical beams in the visible range as well as the non-visible spectralrange such as UV or IR.

[0075]FIG. 8 shows the structure of another element according to theinvention in which, based on the one in FIG. 5 and analogously to FIGS.6 and 7, the continuous layer system 7 or 7 a or 7 b is covered by anadditional body 24″ and a cement film.

[0076]FIG. 9 shows the intersection area on the element according to theinvention, for example, as shown in FIG. 5, in which the layer system 7or with respect to FIG. 7, 7a or 7 b is additionally coated, for examplewith a protection layer system 40.

[0077] Finally FIG. 10 shows the intersection area resulting in theproduction of a structure according to FIG. 3, that is, particularly anX-cube, where the continuous layer system 7 is preferably designed as ared reflection system. An analogous element indicated with the referencemarks ‘a’ or ‘b’ is obtained based on FIG. 6 or 7.

[0078]FIG. 11 shows such a generalized optical element 42 according tothe invention; the professional readily recognizes the multitude ofpossibilities that are opened by this invention.

[0079] In particular in the X-cube production with 90 degree blanks themore accurate machinability of mutually opposed surfaces, the cementingof the blanks, the joint coating and surface finishing and, preferably,the singularization into individual optical elements as the last stepaffords a considerable reduction of the manufacturing costs. It alsoresults in elements with significantly fewer optically effective faultlocations when we take into consideration that in the proposed processthe delicate, centrally located 90 degree edges are never exposed.

[0080] Dielectric layer systems with at least one dielectric layer arepreferably used as optically effective layer systems, particularly inthe production of X-cubes. Suitable coating processes are theaforementioned, sufficiently cold processes. Of course, elements can bemanufactured that are effective in spectral ranges other than visiblelight, for example in the UV or IR range, and in addition to colorsplitting layer systems, also reflection layer systems, antireflectionlayer systems, or polarization layer system can be used or integrated.In particular X-cubes used in projection systems can be manufactured forwhich high-precision, low-cost optical elements are required.

What is claimed is:
 1. A method for manufacturing an optical device,comprising the steps of: providing at least two sub-bodies of a basebody; providing at each of said at least two sub-bodies a surface sothat said surfaces of said at least two sub-bodies are complementary toeach other and snugly fit on one another; providing along at least oneof said complementary surfaces a first layer system, defining an opticallayer system; joining said sub-bodies along said complementary surfacesso as to embed said optical layer system between said sub-bodies andthus forming an assembled sub-body; machining a continuous surface onsaid assembled sub-body and at a predetermined angle to saidcomplementary surfaces and said embedded layer system where the latterabut at said machined continuous surface; and providing a second layersystem along said continuous surface.
 2. The method of claim 1,comprising the step of joining at least two of said assembled sub-bodiesand jointly machining said continuous surface on said at least two jointassemble sub-bodies.
 3. The process of claim 2, thereby providing saidsecond layer system jointly along said machined continuous surface ofsaid at least two join assembled sub-bodies.
 4. The process of claim 1,comprising the step of depositing said second layer system on saidmachined continuous surface.
 5. The process of claim 1, furthercomprising the step of providing a further sub-body and machining atsaid further sub-body a further continuous surface which iscomplementary to said continuous surface of said assembled sub-body andjoining said further sub-body to said assembled sub-body along theircontinuous surfaces, thereby providing said second layer system at leastto one of said continuous surfaces.
 6. The process of claim 5, furthercomprising the step of selecting as said further sub-body and said firstlayer system of said further assembled sub-body are arranged mutuallyopposed at said second layer system.
 7. The process of claim 6, whereinsaid first layer systems of said one assembled sub-body and said firstlayer system of said further assembled sub-body are arranged mutuallyopposed at sid second layer system.
 8. The process of claim 7, furthercomprising the step machining said continuous surfaces of said twoassembled sub-bodies to be plane and providing said first layer systemsat said two assembled sub-bodies to abut substantially at a right angleon said second layer system.
 9. The process of claim 1, furthercomprising the step of dissecting said one or said second one andfurther assembled sub-body in such a way that the dissected elementscomprise respectively said first and second layer systems.
 10. Theprocess of claim 5, further comprising the step of dissecting said oneor said second one and further assembled sub-body in such a way that thedissected elements comprise respectively said first and second layersystems.
 11. The process of claim 6, further comprising the step ofdissecting said one or said second one and further assembled sub-body insuch a way that the dissected elements comprise respectively said firstand second layer systems.
 12. The process of claim 1, wherein machiningof said continuous surface comprises at least one of lapping or ofpolishing.
 13. The process of claim 5, wherein machining of saidcontinuous surface comprises at least one of lapping or of polishing.14. The process of claim 6, wherein machining of said continuous surfacecomprises at least one of lapping or of polishing.
 15. The process ofclaim 1, further comprising the step of simultaneously machiningcontinuous surfaces on opposite sides of said sub-bodies or of saidassembled sub-bodies.
 16. The process of claim 2, further comprising thestep of simultaneously machining continuous surfaces on opposite sidesof said sub-bodies or of said assembled sub-bodies.
 17. The process ofclaim 6, further comprising the step of simultaneously machiningcontinuous surfaces on opposite sides of said sub-bodies or of saidassembled sub-bodies.
 18. The process of claim 1, further comprising thestep of joining at least one of sub-bodies and of assembled sub-bodiesby one of cementing and of wringing.
 19. The process of claim 5, furthercomprising the step of joining at least one of sub-bodies and ofassembled sub-bodies by one of cementing and of wringing.
 20. Theprocess of claim 6, further comprising the step of joining at least oneof sub-bodies and of assembled sub-bodies by one of cementing and ofwringing.
 21. The method of claim 1, wherein at least one of said layersystems is deposited as a dielectric layer system.
 22. The process ofclaim 21, wherein said deposition is performed by at least one of aplasma-aided and of an ion-aided coating process.
 23. The method ofclaim 21, wherein said deposition is performed by one of sufficientlycold PVD and of a sufficiently cold PECVD process.
 24. The process ofclaim 21, wherein said deposition is performed by a cold coating processwhich establishes a substrate temperature of at most 150° C.
 25. Theprocess of claim 24, wherein said temperature is 80° C. at most.
 26. Theprocess of claim 1, further comprising the step of providing at leastone of said layer systems with at least one dielectric layer.
 27. Themethod of claim 1, further comprising the step of providing at least oneof said layer systems as one of a reflection layer system, of apolarization layer system, of a color splitting system and of anantireflection system.
 28. The method of claim 5, further comprising thestep of providing at least one of said layer systems as one of areflection layer system, of a polarization layer system, of a colorsplitting system and of an antireflection system.
 29. The method ofclaim 6, further comprising the step of providing at least one of saidlayer systems as one of a reflection layer system, of a polarizationlayer system, of a color splitting system and of an antireflectionsystem.
 30. The process of claim 1, further comprising the step ofproviding said second layer system as a red reflection system.
 31. Theprocess of claim 5, further comprising the step of providing said secondlayer system as a red reflection system.
 32. The process of claim 6,further comprising the step of providing said second layer system as ared reflection system.
 33. The process of claim 30, further comprisingthe step of providing said second layer system for S-polarized light atan incidence angle of 45° relative to the layer system.
 34. The processof claim 5, further comprising the step of bonding at least saidassembled sub-body and said further sub-body to get a resulting cuboidbody and then sub-dividing the resulting cuboid body into individualcuboid bodies.
 35. The process of claim 6, further comprising the stepof bonding at least said assembled sub-body and said further sub-body toget a resulting cuboid body and then sub-dividing the resulting cuboidbody into individual cuboid bodies.
 36. The method of claim 6, whereinthe resulting body being an X-cube.
 37. The method of claim 35, whereinthe resulting body being an X-cube.